Ascending pathways mediating somatoautonomic reflexes in exercising dogs

Area of Science:

• Neuroscience
• Cardiovascular Physiology
• Exercise Physiology

Background:

• Understanding the neural control of cardiovascular responses during exercise is crucial.
• The specific spinal pathways involved in exercise-induced cardiovascular reflexes, particularly during ischemia, are not fully elucidated.

Purpose of the Study:

• To identify the ascending spinal pathways that mediate somatocardiovascular reflexes during exercise in dogs.
• To investigate the role of the lumbar spinal cord in cardiovascular adjustments to hindlimb exercise and ischemia.

Main Methods:

• Unanesthetized dogs were trained to run on a treadmill.
• Lesions were placed in specific areas of the lumbar spinal cord (dorsolateral sulcus and funiculus at L2).
• Cardiovascular responses (heart rate, blood pressure) were monitored at rest and during hindlimb running with and without transient iliac artery occlusion (ischemic exercise).

Main Results:

• Hindlimb exercise combined with ischemia significantly augmented pressor response and tachycardia compared to exercise alone.
• Lesions in the dorsolateral sulcus and dorsolateral funiculus at L2 markedly reduced cardiovascular responses during simultaneous exercise and ischemia.
• Cardiovascular responses to nonischemic exercise and baroreceptor reflexes were unaffected by the spinal lesions.

Conclusions:

• Ascending spinal pathways mediating cardiovascular responses to ischemic exercise are located within the lateral funiculus, including the dorsolateral sulcus and dorsolateral funiculus.
• These pathways are critical for integrating cardiovascular adjustments during strenuous exercise involving muscle ischemia.